Stitch control for sewing-machines



J. A. FLANAGAN. STITCH CONTROL FOR szwm MACHINES. APPLICATION FILED MAY 5| I9I9- R EIIEWED JUNE I, IQZI- 1,387,140. atentedAug. 9, 1921.

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wfygw My J. A. FLANAGAN. STITCH CONTROL FOR sswmc MACHINES. v APPLICATION FILED MAY5.19!9- RENEWED JUNE 1, I921. 1,387,140, Patented Aug. 9, 1921.

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v au m' aa M cillating-reciprocating pitman L FLANAGAN, OF TORONTQDNTAR'IO, CANADA.

Specification of Letters Patent.

s'rrreai common roe snwme-macnmns- Patented Aug. 9, 1921.

' Application filed May 5, 1919, Serial No. 294,675. Renewed June 1, 1921. Serial No. 474,299.

To aZZ whom it may concern:

Be it known that I, JAMES ALEXANDER FLANAGAN, a subject of the King of Great Britain, residing at Toronto, in the county of York and Dominion of Canada, have invented a certain new and useful Improvement in Stitch Controls for Sewing-Machines, of which the following is a full, clear, and'exact description.

One of the objects of this invention is to construct a sewing machine with mechanism which, while the needle shaft is moving at uniform speed, will rotate the hook shaft at variable speeds; as for example, it will revolve the hook relatively slowly when pickingup the loop to carry it around the shuttle, then gradually and continually increase the rapidity of revolution during the formation of the loop and its delivery from the hook, and finally gradually and continually reduce the speed for the picking up of the next loop; this object being attained by providing the hook shaft with a grooved crank arm and the needle shaft with an osslidably mounted on a rocking fulcrum and having a sliding connection with the crank arm.

A further object of the invention is to control the'direction of feed and the length of the stitch, this object being attained by the use of an arczzate'link rockable on a fixed pivot,actuated byapitman receiving motion from the needle shaft, and imparting motion to the feed shaft by means of a connecting rod having an adjustable oonnectlon with the link, as hereinafter set forth and particularly pointed out in the claim.

In the accompanying drawing illustrating the invention, in the several figures of which like parts are similarly designated, Figure 1 is a longitudinal section. of a sewing machine, with some of the parts in section and others broken out. Fig. 2is a cross section on line 2-2 of Fig. 1. Fig. 3 is a diagrammatic elevation of the compound, lever mechanism, showing different adjustments.

The bed-plate 1, overhanging arm 2, needle-shaft 3, hook-shaft 4 and their adjuncts may be of any usual or approved construction and arrangement, and so also may be other parts shown in the drawing and not otherwise specifically described herein.

5 is a rock-shaft, made hollow and surrounding the hook-shaft 4, and having at its front end aciank arm 6 to engage the feeddog, said rock-shaft forming part of the in-- vention of my case filed February 4, 1919, Serial No. 274,902. LThis shaft 5, herein referred to as the feed, shaft, has at its rear end a crank arm 7 set quartering or otherw1se thereon with'r'elation to the crank arm 6. The hook-shaft 4 has a grooved crank arm 8 at its rear end slidingly engaged by-a roller 9 on the end of a connecting rod 10 which connects with a crank 11 on theneedle shaft and is operated bythe latter to cause the revolution of the hook shaft. Between its ends the connecting rod 10 is formed with an elongated slot 12, and within this slot is a rocking member or fulcrum 1 3 loosely mounted upon a fixed pivot-pin 14-, the inner end of saidpin being screwed or otherwise fixed in a support 15 projecting within the hollow upright of the overhanging arm and preferably east integral with one side of it. During the rotation of the needle shaft the crankll and fulcrum .13 impart an travel to and from the axis of the hook shaft i in its sliding connection with the crank arm 8. When the hook is picking up the loop the roller 9 is at or near the outer end of the crank arm 8, and is then revolving the hook shaft at a relatively slow speed. When the loop has been picked up the roller 9 moves inward along the crank arm 8 toward the axis of the hook shaft, and gradually increases the speed of revolution until the maximum speed of rotation is attained and then moves outwardly along the arm to again decrease the speed of rotation to enable the hook to pick up the next loop. 16 is an arcuate link pivoted centrally or thereabout on a screw or other pivot 17 fixed to the upright part of the arm 2. This link has an undercut or equivalent groove 18 in its face to receive a roller 19 on the upper end of a connecting rod 20 which is pivoted to the crank arm 7, and this roller 19 enters and works in the groove 18 of the link 18.

, The link 16 has applied to one of its ends a I which is pivoted on a pin 26 supported at opa vertical slot 29 in said upright and provided with a clamping nut to hold the slide in its adjusted position. As the bell crank lever is rocked by the adjustment of the slide 28, it serves to selectively shift the roller end of the connecting rod 20 to one side or the other of the pivot or axis of the link 16, and thereby change the direction of movement of the feed dog and consequently that of the stitching. The adjust ment of the slide also permits the adjustment of the roller at points between the axis of the link 16 and one or the other of its ends so as to vary the throw of the connecting rod 20, and consequently the length of the arc of movement of the crank arm 7 and the length of movement of the feed dog and length of stitch. The full and dotted lines, Fig. 3, indicate possible variations of the sort referred to.

It is at times desirable to adjust the handon its shaft, and for this purpose I fix a friction clutch disk 31 upon the needle shaft and provide it with an internally screwthreaded sleeve 32. The wheel 33 is made with a hub which fits on the sleeve 32 and has face contact with the disk 31, and a thumb-screw 34 is provided to engage the 'screwthreaded sleeve and the hub of theintimate contact with disk 31 or to free it from such contact.

Variations in details of construction and arrangement of parts are contemplated as being within the principle and scope of the invention as hereinafter claimed.

What I claim is In a stitch control mechanism for sewing machines, a driving mechanism, a driven feed shaft, and a compound lever mechanism interposed between and connected with these shafts, comprising an arcuate rocking link provided with an undercut groove, a slotted.

link having one end connected with the feed shaft, and having at its other end a roller movable lengthwise of said groove for varying the length and direction of the feed, a link pivotally connected at one end with the arcuate link, and at the other end with the driving mechanism for imparting the pin movable in the slot of the first mentioned link, and having its other arm forked, and a slide engaging the forked arm of the bell crank lever and moving it to adjust the roller in the arcuate link. 4

In testimony whereof I have hereunto set my hand this first day of May, A. D. 1919. JAMES ALEXANDER FLANAGAN.

Witnesses:

HENRY L. DALE, M. ROBINSON.

rocking motion to the feed shaft, a bell crank having one arm provided with a 

